7ell
From Proteopedia
In situ structure of capping enzyme lambda2, penetration protein mu1 of mammalian reovirus capsid asymmetric unit.
Structural highlights
FunctionMU1_REOVD Major outer capsid protein involved in host cell membrane penetration. In the endocytic compartment, outer-capsid protein sigma-3 is removed by cathepsin proteases, which exposes the viral membrane-penetration protein mu-1. Both myristoylated peptides mu-1N and phi are released during infectious subvirion particles (ISVP) formation in the endosome. They associate with host membranes and mu-1N induces permeabilization and delivery of transcriptionally active viral particles into the host cell cytoplasm. Seems to induce apoptosis in the host cell (By similarity). The viral outer shell polypeptides, of which mu-1 is one, impose structural constraints that prevent elongation of nascent transcripts by the RNA-dependent RNA polymerase lambda-3.[1] Publication Abstract from PubMedMammalian reovirus (MRV) is the prototypical member of genus Orthoreovirus of family Reoviridae. However, lacking high-resolution structures of its RNA polymerase cofactor mu2 and infectious particle, limits understanding of molecular interactions among proteins and RNA, and their contributions to virion assembly and RNA transcription. Here, we report the 3.3 A-resolution asymmetric reconstruction of transcribing MRV and in situ atomic models of its capsid proteins, the asymmetrically attached RNA-dependent RNA polymerase (RdRp) lambda3, and RdRp-bound nucleoside triphosphatase mu2 with a unique RNA-binding domain. We reveal molecular interactions among virion proteins and genomic and messenger RNA. Polymerase complexes in three Spinoreovirinae subfamily members are organized with different pseudo-D(3d) symmetries to engage their highly diversified genomes. The above interactions and those between symmetry-mismatched receptor-binding sigma1 trimers and RNA-capping lambda2 pentamers balance competing needs of capsid assembly, external protein removal, and allosteric triggering of endogenous RNA transcription, before, during and after infection, respectively. Asymmetric reconstruction of mammalian reovirus reveals interactions among RNA, transcriptional factor micro2 and capsid proteins.,Pan M, Alvarez-Cabrera AL, Kang JS, Wang L, Fan C, Zhou ZH Nat Commun. 2021 Jul 7;12(1):4176. doi: 10.1038/s41467-021-24455-4. PMID:34234134[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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